Aeroman - I am beginning to think that taking the Aero down as is and hoping for the best is a good plan; just wanted it in great conditions!
Would love the shower cap for that purpose - as it happens I am with my parents in Virginia Water this weekend so could easily drive over to get it on Sunday (and would love the opportunity to see your car) - if you really will accept no money, could I take you out for a drink to say thank you?
That shower cap could mean the trip down through France in an Aero with a leaky roof can be contemplated (even if it will clash with the blue paintwork

)